Cardiac surgery includes heart surgeries that require extracorporeal circulation (ECC), that is, the assistance of the cardiopulmonary machine, and those surgeries that are performed directly on the beating heart and do not require ECC. The term "cardiac surgery" can include coronary artery bypass graft surgery (CABG) with ECC, CABG directly on a beating heart, minimally invasive direct coronary artery bypass surgery (MIDCAB), heart valve repair surgery or valve replacement surgery, and surgery to correct either an atrial septal wall or ventricular septal wall defect.
The term "cardiac devices" can include surgical apparatus and devices used during "cardiac surgery". The term "coronary organs includes the heart, the heart's arteries and veins, the surrounding tissue and vessels, in particular the mediastinum, the pericardium, the thymus, the pleura, and the space between the two lungs. In this document, unless otherwise stated, a reference to arterial surgery, or to a target artery, are intended to encompass reference to veins as well, under the general field of vascular surgery.
In recent years, the drive for cost effective surgery has intensified the need to develop surgical apparatus and medical approaches that keep healthcare costs manageable, while also allowing the treatment of older patients where economic justification may previously have been deemed marginal. Surgical apparatus that improves the efficiency of surgeons while reducing operating times, and improves the efficacy of the surgical intervention is desirable.
The recent interest in and search for less invasive surgery has placed emphasis on cardiac surgery as well. A feature of heart surgery is that the beating motion of the heart tends to complicate the delicate surgical intervention.
Heart surgeries have been performed with the support of a cardio-pulmonary machine, whereby the patient's blood was oxygenated outside the body, through extracorporeal circulation (ECC). This permits coronary operations on the arrested heart, meaning that a surgeon can manipulate and operate on a still heart. During traditional CABG surgery, this enables the surgeon to position the heart for best access to the target artery, requiring grafting.
ECC is highly invasive, particularly in coronary artery bypass graft (CABG), valvular surgery, and repair of atrial and ventricular septal wall defect. The advantages offered with ECC have been offset by the morbidity (complications) and mortality related to the ECC itself. The inflammatory response, as well as the systemic microembolisms generated by ECC, induce to some extent a dysfunctional state of the brain, lungs, and kidneys, which tends to increase with the aging of the patient. As a result, alternate CABG procedures that do not rely on the very invasive use of ECC offer distinct advantages.
Canadian patent application 2,216,893 of Cartier and Paolitto, describes apparatus for performing coronary surgery without the very invasive cardio-pulmonary machine. Canadian patent application 2,216,893 also describes surgical apparatus having "coarse" and "fine" adjustments to permit a contacting member to be placed relatively accurately in a large number of positions and orientations within a surgical working volume. The "coarse" adjustment of the heart stabilizer is achieved through linear and angular displacements, which locate a first articulation assembly in the nature of a cylindrical post on a base retractor. The "fine" adjustment of the contacting member is achieved through linear and angular displacements of a second positioning rod with respect to the first positioning rod, through a second articulation assembly.
In some cardiac interventions, it is desirable to avoid or override the coarse and fine adjustment, and to allow the simultaneous setting of all the motion degrees of freedom available in both the spherical clamp and cylindrical post, through a single point control manipulation means, thereby linking all said degrees of freedom. It is also advantageous for the contacting member, through the surgical apparatus to serve to position and orient at least a portion of the coronary organ within surgical workspace.
To achieve complete revascularization in a single surgical procedure--that is, to revascularize or treat all surgically reconstructable diseased arteries in one intervention--it may be desirable to position and orient the beating heart to obtain access to the posterior artery beds, through the same heart contacting instrument which will eventually serve to stabilize that portion of the beating heart. As a result, a surgical approach and associated apparatus which can manipulate the beating heart without inducing tissue trauma and hemodynamic instability by allowing the surgeon to exploit all motion degrees of freedom of said apparatus, through a single point control manipulation means prior to securing the entire surgical set-up, is advantageous. It is also advantageous for that apparatus to be moveable to a position in which the heart can be stabilized and in which the surgeon's field of view remains substantially unobstructed.
Prior to rigid securing of entire surgical set-up, a surgical apparatus that allows its components to remain substantially attached (while keeping their relative positions and orientations), but free to rotate, slide, and pivot when movement loads are imposed by the surgeon through the manipulation means, offers distinct advantages.
In certain surgical interventions, it may be advantageous to limit the full range of motion available in one or more of the degrees of freedom of the surgical apparatus. It would be advantageous to have an adjustment means capable of setting a "bias"--a limited range of motion within the full range of motion of that specific degree of freedom that the apparatus could otherwise achieve, were the bias not present. Furthermore, it would be advantageous to have a surgical apparatus which allows the set bias to be re-adjusted to a new setting or overridden entirely, without disengaging the constituent components used to achieve said bias, or disengage a part of the surgical set-up.
In surgical interventions, especially in a beating heart approach, where the risk of inducing heart tissue trauma is present, it is advantageous to have a surgical apparatus which enhances the sensitivity of the surgeon to the loads imposed by the contacting means on the coronary organs.
In beating heart CABG, the use of pericardial sutures are sometimes used to help "verticalize" the heart in addition to the heart stabilizer devices described in Canadian patent application 2,216,893. It would be advantageous to anchor these sutures to the base retractor or to structure outside the surgical workspace, without limiting the range of motion of the positioning means namely the articulated arm assembly, once said sutures have been set. This may tend to be beneficial in multi-vessel coronary revascularizations that require the resetting of the positioning means and at least a part of the surgical set-up, in subsequent grafting of different arteries.
In beating heart surgery, the pulsating effect of the heart on the stabilization apparatus over prolonged periods, can at times necessitate re-adjustment of the surgical set-up. In addition, the surgeon's need to vary the contact forces on the heart depending on the surgical intervention (i.e. grafting, incision, etc.), may occasionally require the re-orientation and re-positioning of the contacting means to ensure optimum stabilization during the entire surgery. Apparatus that allow easy and expedient repositioning and reorientation of the contacting means offer distinct advantages. This would be particularly so with features that facilitate use of the surgical apparatus by a person wearing surgical gloves.
It would also be advantageous to have an apparatus and method for encouraging the isolating and exposure of a target artery requiring anastomosis through the arterial window formed by the geometry of a coronary stabilizer. In beating heart surgery, the coronary stabilizer immobilizes or stabilizes a portion of the heart tissue, and consequently may tend to immobilize the target artery straddled by a coronary stabilizer. It is desirable for the target artery to be isolated and exposed in a manner that causes it to rest proudly through the arterial window of the coronary stabilizer, thereby facilitating the surgery. It would be advantageous to have a surgical apparatus of a design which may tend to reduce or minimize the amount of distortion, deflection, or restriction imposed to the underlying heart tissue, thereby tending to preserve the natural beating function of the heart under mechanical stabilization.